Hi, I'm trying to use std::regex and it's failing with even the simplest patterns: #include <regex> int main(int, char* argv[]) { std::regex rex("\\d"); return std::regex_match("1", rex); } g++ -std=c++11 rex_test.cpp -o rex_test ./rex_test terminate called after throwing an instance of 'std::regex_error' what(): regex_error Aborted (core dumped) GCC version: gcc version 4.8.1 (Ubuntu/Linaro 4.8.1-10ubuntu9). GCC 4.7.3 exhibits the same behavior. Replacing "\\d" pattern with "[0-9]" results in the same failure. It works with Boost.Regex, Boost.Xpressive and with clang 3.4 & libc++. Am I doing something wrong? If my use of std::regex is correct then for me this basically means that std::regex is unusable. In this case, could we define BOOST_NO_CXX11_HDR_REGEX in Boost.Config for all versions of libstdc++?